Hmm that makes sense. I was aware of the event I just didn't realize that it impacted North America to the extent to erase all history. Still though, the younger dryas occurred approximately 10k years ago so I would think there would still be lots of history to discover in the US.
It's a catastrophists model. It wiped much of the world clean but NA was more or less ground zero. The geological evidence he has is mind boggling and easy to understand, ripples across a landscape that could only be left by unimaginable sized waves bigger than anything in the historical record. All ancients have a flood myth.